Office (OOXML) / .XLSX malware analysis — malicious · 57857533a81a13b4

MALICIOUS

Office (OOXML) / .XLSX

68.0 KB Created: 2021-03-15 18:25:48 UTC Authoring application: Microsoft Excel 16.0300

MD5: bd4ce5409a78f57c035f03c448fd3b19 SHA-1: f8b559eb5eb472852437c5f3478aa24e5cfd0915 SHA-256: 57857533a81a13b4eaa17f3516d5c5a9be138ee5dfa7b2c73788417061c9dbc4

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros within the XLSX file. While the macro content is truncated and heavily obfuscated, the presence of such macros strongly suggests an intent to execute arbitrary commands. This is a common technique for delivering secondary payloads, making the overall attack pattern a macro-based execution of external code.

Heuristics 1

Excel 4.0 macro sheet (1 sheet(s)) critical OOXML_XLM_MACROSHEET

Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `5d06ae193ecb87177f4c53c0edd10f6ea0f44aa3fc6bad917ad9cb6f52865865`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	90467 bytes

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